Graphical description of the study design and experimental cohort. Patients eligible for this study were selected according to the criteria defined in the upper panels of this figure. Selected patients had a degree of BM involvement of <25%, age at diagnosis between 1 and 18 years, BCP-LBL cellular morphology, and positivity for terminal deoxynucleotidyltransferase (TdT) and CD19 and/or CD79a. DNA and RNA were extracted from tissue biopsies of selected patients and processed for DNA and RNA next-generation sequencing (NGS) analyses. The results of these analyses were integrated to assign lymphoma subtypes and define molecular differences between the BCP-LBL cohort here described and publicly available data obtained from pediatric patients with BCP-ALL (Brady et al⁷). The panel below shows for each of the 97 patients information about the age group, sex, and location (Loc.) of the biopsy used for molecular analyses, and if the material was available as FFPE or FF. The figure also shows the tissue processing center (DE, Germany; NL, The Netherlands) and NGS analysis performed (WES, whole exome sequencing; RNA, whole-transcriptome sequencing; EuroCl., targeted sequencing of selected genomic regions using the EuroClonality-NDC Assay).